1. Field of the Invention
This invention relates to a head positioning method employed in a recording apparatus for shifting a recording head in a given direction relative to a record bearing medium for recording in each of shifted positions on the medium.
2. Description of the Prior Art
The known recording apparatuses include the kind having a movable head for recording, on a rotary recording medium such as a magnetic disc or a magnetic cylinder, a unit length of information (such as one field or one frame portion of a video signal or the like) in each of recording tracks which are formed in a concentric circular shape or in an annular shape on the recording medium, accordingly, as the information is recorded. In preventing overlapped recording in recording the information with the apparatus of this kind, for example, the head must be first accurately positioned at an unrecorded part of the recording medium. In accordance with a known method employed in the conventional apparatus, a desired recording position of the head on the recording medium is checked for the presence or absence of any previous record therein before recording. In the event of the presence of a previous record, the head is shifted to a next desired recording position. The head is thus positioned at an unrecorded part of the recording medium with such a check-up process repeated before recording. An example of this method was disclosed in Japanese Laid-Open Patent Application No. SHO 54 -140515.
With the head positioning method of the prior art arranged as described above, in case that a record in an intermediate recording track has been erased, the head is first positioned at that erased track. Therefore, in shifting the head to a next recording position after completion of recording, the presence or absence of a record must be detected again at every point to which the head is shifted. The possibility of overlapped recording otherwise cannot be eliminated. In that instance, it takes a long period of time in bringing the head to an unrecorded part for a next recording process. Then, a good opportunity for recording (a shutter chance in the case of a camera) would be missed. Further, it becomes hardly possible to adequately carry out continuous recording, such as still video recording for several consecutive fields per second or for several consecutive frames.